606 LIGHT AND ENERGY LOSSES IN PROJECTION [Cn. XIV 



absorbed in the water-cell heats the water, but water is peculiarly 

 adapted for this purpose for it is the best known absorbent of the 

 infra-red, "heat rays." 



Water is easily obtained and put into the cell. It has the highest 

 specific heat of any known substance; i. e., a given quantity of 

 water will absorb more energy when being warmed a given amount 

 than will anything else. If the water in a water-cell becomes so 

 hot that it gives off bubbles, a cool cell can be substituted for it. 

 Cooling a cell by the circulation of cold water through it has not 

 proved successful. 



The temperature of the water has no appreciable effect upon the 

 energy absorption, boiling water serving as well as ice water. The 

 energy transmission for a water-cell was found when hot (80 C.) 

 to be 18.4%; when cold (22 C.) 19.2%. The water was slightly 

 turbid, being more so when hot than cold. 



849. The energy transmission of layers of water of different 

 thickness. The source of light is the crater of the right-angle 

 carbon arc. 



WITH 12 AMPERES DIRECT CURRENT 



WITH 15 AMPERES ALTERNATING CURRENT 



8.00 cm. 



14-4% 



